Digital gain vs analog gain

I am not suprised at your findings. I have always been advised that one should set iTunes at full volume. Then set amp such that your preamp can be run between 10-2 o'clock depending on desired volume ( therefor around 12) . This is usually the sweet spot on most variable pots used in a preamp. 

One problem you have is the total gain you have between preamp and amplifier causing you to attenuate much of the available gain in the amplifier. Your compromise seems the best fit. 

Then set amp such that your preamp can be run between 10-2 o'clock depending on desired volume ( therefor around 12) . This is usually the sweet spot on most variable pots used in a preamp. 

Data?

I have always been advised that one should set iTunes at full volume.

Compression is LOW-FI See ieLogical Lossy for a real life iTunes example

Lossy music on a high resolution system can be literally nauseating due to the constant atemporal image shift.

Two things.

First, my listening enjoyment on a system costing only $2K between a recapped old Crown PS200 and the new Wharfedale Lintons, a Bluetooth DAC and unpowered preamp switch with a pot has benefited from all this info. 

Basically, pushing in higher level digital and living with analog attenuation of 50% at the preamp and 25% at the main amp has pleased the clever Peter Comeau designed heritage speakers and delivered more detail to my listening. So thanks!

Second, I’m interested in the issue of lossless iTunes format from Apple. My little BlueMeHD Bluetooth DAC combination is a well reviewed accessory for older amps, and seems to compare well to the more expensive TASCAM CD400U rack Mount in my other stereo downstairs in our living room.

My best reading so far, however, sounds like Apple does not say that their format survives Bluetooth transmission. I have a couple iPads snd I could potentially rig one of then as a hard connected high speed WiFI input device. Is that worth a new thread?

This is a really interesting thread.  I recently decided to try a tube pre (Zesto Leto) in my set up.  It pairs with my balanced DAC (MHDT Pagoda), SS Amp (Krell XD Duo), Alta Audio Alec’s and the streaming is handled by a Auralic Aries G1 streamer. 
 

My other Pre is a Krell Illusions ii.  

When I introduced the Tube Pre, found the synergy / match on again / Voltage was off - as noted on this thread some Balanced DAC’s come out hot and that’s the case with my DAC.  Without any adjustment I barely have to move the volume on the Pre.  What this causes is similar results to having too low a gain, I’ve got a hum and the highs overpower the mid’s / bass.  When I put a attenuator into the mix at the input stage of the Amp (- 10 DB) dramatically lowered the hum and balanced off the sound.  Even at - 10 DB it’s still a bit hot, can’t take the volume knob above a quarter turn.  I really like the sound of the tubes on the front end so my solution long term is having a custom box built that will allow for 3 different setting on voltage and a bypass setting.  I could send the Pre in to Zesto and have the gain adjusted but then if I decide to switch amps or my DAC I may have mismatch the other way.  This set up will allow some flexibility.  
 

The moral of my story, findings is that the synergy / marriage of the pre and amp as it relates to gain / voltage is important.  Can have a significant impact on sound quality and the noise floor.  Most will point toward issues when something in the chain is too low but if too high, causes issues as well. 

Happy Holidays and Good luck on your Audio Journey!